1. Field of the Invention
This invention relates to the provision of pressurized fluids used in well operations and, more particularly, to an apparatus and method for providing a controllable supply of fluid, and optionally electrical power and/or communication signals, to a subsea well equipment.
2. Description of Related Art
In the production of fluids from a subsea hydrocarbon reservoir, it is often desired to perform a workover operation to improve or verify certain performance of the well and/or the subsea equipment associated with its operation, such as a subsea Christmas tree, i.e., an assembly of valves, spools, and fittings, used for controlling the operations of a subsea well. For example, in a typical workover operation, the operations of the subsea Christmas tree can be controlled without the well's production system in operation to determine if the tree is operating correctly. Such a workover operation can be performed after the well has been in production for some time, or a similar operation can be performed just prior to completion and production operation of the subsea well.
A conventional method for performing such a workover includes the use of an Intervention Workover Controls System (IWOCS) that supplies hydraulic power to operate the various functions of the tree. The IWOCS typically includes a hydraulic power unit, pumps, and accumulator banks that provide the hydraulic power as a supply of pressurized hydraulic fluid. This equipment is located topside, and the IWOCS also includes a workover umbilical that transmits the hydraulic fluid, electrical power, and communication signals from the topside to the subsea tree.
The workover umbilical and rig required for the IWOCS increase the cost of that system, and the capital and operational costs can be significant, especially for workovers of deep subsea wells. Further, the IWOCS generally requires significant space on the topside facility.
One alternative to IWOCS is a Remote Workover Control System (RWOCS), which is similar to IWOCS except that some of the equipment necessary for the workover may be located in the water, e.g., attached to a remotely operated vehicle. Such as system typically still requires a significant amount of space on the topside facility, e.g., for providing the umbilical to the subsea equipment for power and/or communication, for equipment associated with the ROV such as a winch and A-frame, and the like.
Thus, there exists a continued need for an improved apparatus and method for providing a controllable supply of fluid, electrical power, and/or communication signals to subsea well equipment, such as for performing workover operations.